The process to appoint the new federal Liberal candidate for Joe Hockey's former seat of North Sydney has been described from those within the party as a "stitch-up" and undemocratic.

With a 15.9 per cent margin, North Sydney is one of the safest federal Liberal electorates in Australia.

The seat was held by the former treasurer for nearly 20 years and now the party is facing a once-in-a-generation opportunity to choose a new candidate.

But some insiders say that opportunity has been missed, and instead of a genuine competition the safe seat is being effectively handed to a party apparatchik, the NSW Liberal Party's acting state president Trent Zimmerman.

Barrister and Liberal Party member Juris Laucis is disappointed in the process, saying that the Liberal Party machine has guaranteed that Mr Zimmerman will win the contest.

"Trent Zimmerman has almost 50 per cent in the bag even before you start the pre-selection voting, and that's not democratic," he told 7.30.

The other two candidates standing against Mr Zimmerman are John Hart, the chief executive of Restaurant and Catering Australia, and Dr Helen Cartledge, an engineer working with the Army.

The candidate will be decided by a vote of 48 members from the North Sydney branch, and around 40 from the Liberal Party's state executive and state council. There would have been 48 from the central branch, but 7.30 understands eight of them have been ruled out on technicalities such as not attending a sufficient number of Liberal Party meetings.

Mr Laucis is a member in the neighbouring Warringah branch. He says a decision by the NSW Liberal Party not to allow all the branch members of North Sydney to vote for a candidate is a mistake.

He risks expulsion from the party by speaking out about the preselection process.

"I'm fully aware that as member of Liberal Party I am not supposed to speak about party matters to the press, however when there is no avenue of complaint within the constitution when you feel the executive are not doing the right thing there is no other choice," he said.

"If it means I get expelled so be it, but it's not really worth being part of a party that does not practice democracy."

'They should look for better candidates'

North Sydney Mayor Jilly Gibson used to be a Liberal Party member, and says supporters are urging her to run in North Sydney as an independent candidate.

"I'm disappointed in the (Liberal Party) pre-selection process," she said.

"It seems as though the rules have been bent a little bit, and if they're going to bend the rules why not bend them in favour of a woman?"

She said she would consider running if she could find a financial backer.

"I'd love the job, and if someone would like to bankroll my campaign, I'll put my hand up for nomination."

North Sydney has been represented by an independent in the past. The seat was held between 1990 to 1996 by Ted Mack.

Mr Mack said he believes that the Liberal Party has not scoured its ranks for the best candidate.

"Whoever is the candidate can be here for 20 to 30 years, so they should look for the best candidate they can possibly find," he told 7.30.

Mr Mack agrees the Liberal Party should involve its grassroots members and the broader public in selecting the next member for North Sydney.

"I think they should look for better candidates," he said.

"I think they should put up four candidates, two women and two men, and let the public decide which one."

The Australian Electoral Commission estimates that the by-election, which will take place on December 5, will cost over $1 million.